The purpose of this proposal is to improve and expand an existing study of fetal death and pesticides exposure during pregnancy. There are a number of pesticides that are thought to have teratogenic/mutagenic potential, and these and other commonly used pesticides are being studied in the San Joaquin Valley of California where there is heavy use of pesticides. The epidemiologic study design is case-control, where cases are fatal deaths that have been identified from certificates of fetal death and controls are live births randomly chosen (within matching variable strata) from the same counties. There are 644 cases of fetal death and 644 control births. The specific aims are as follows: 1) increase the questionnaire response rate by means of phone calls and mailings (the response rate to date for subjects for whom we have good addresses is 55%), 2) locate study subjects who we have not been able to contact due to outdated addresses on certificates of birth and fetal death (24% of the study subjects), 3) geocode the residential addresses during pregnancy for linkage to pesticide application data for restricted pesticides, 4) develop computer algorithms for determining sections adjacent to place of residence for the pesticide linkage (a section is a square mile unit within township and range), 5) code data on medical, environmental, and other factors that were collected on the questionnaire, and 6) analyze the relationship of low birth weight and pesticide exposure within the control group of live births.